title: Fucoidan cures infection with both antimony-susceptible and -resistant strains of Leishmania donovani through Th1 response and macrophage-derived oxidants.
abstract: OBJECTIVE
  The aim of this study was to evaluate and characterize the antileishmanial efficacy of fucoidan, a polyanionic sulphated polysaccharide from brown algae, in experimental infections of BALB/c mice with antimony-susceptible (AG83) and -resistant (GE18ER) Leishmania donovani.
  
  
  METHODS
  The effect of fucoidan was assessed against intracellular parasites in cultured macrophages and in suppressing splenic and liver parasite burdens in a BALB/c mouse model of visceral leishmaniasis by microscopic evaluation of surviving intracellular amastigotes stained with Giemsa. To evaluate the type of immunological responses, real-time PCR and ELISA were performed for various Th1 and Th2 cytokines in both in vitro and in vivo infected conditions. To determine the effector mechanism, reactive oxygen species (ROS) and NO were measured in fucoidan-treated animals by H(2)DCFDA-based fluorometric analysis and Griess reaction, respectively.
  
  
  RESULTS
  In addition to having appreciable inhibitory effect on amastigote multiplication within macrophages (>93% inhibition at 50 μg/mL), complete elimination of liver and spleen parasite burden was achieved by fucoidan at a dose of 200 mg/kg/day given orally, 3 times weekly, in a 6-week mouse model of both antimony-susceptible and -resistant strains. This curative effect is associated with switching of T cell differentiation from Th2 to Th1 mode. Further, splenocytes of fucoidan-treated infected (AG83 and GE18FR) mice generated significantly enhanced levels of superoxide and NO. Not only was this treatment curative when administered orally 15 days post-infection, but it also imparted resistance to reinfection.
  
  
  CONCLUSIONS
  These results suggest the effectiveness of fucoidan as potent immunomodulator for controlling both antimony-susceptible and -resistant visceral leishmaniasis.
authors.affiliation: Molecular Cell Biology Laboratory, Infectious Diseases and Immunology Division, Indian Institute of Chemical Biology, Kolkata, India.
authors.forename: Susanta
authors.initials: S
authors.lastname: Kar
authors.forename: Gunjan
authors.initials: G
authors.lastname: Sharma
authors.forename: Pijush K
authors.initials: PK
authors.lastname: Das
mesh_terms: D000818:Animals; D000981:Antiprotozoal Agents / Q000008:administration & dosage* / Q000494:pharmacology; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007893:Leishmania donovani / Q000187:drug effects*; D007898:Leishmaniasis, Visceral / Q000188:drug therapy*; D008099:Liver / Q000469:parasitology; D008264:Macrophages / Q000276:immunology* / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000032:analysis / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D011134:Polysaccharides / Q000008:administration & dosage* / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000032:analysis / Q000494:pharmacology; D012376:Rodent Diseases / Q000188:drug therapy; D013154:Spleen / Q000469:parasitology; D018417:Th1 Cells / Q000276:immunology*
chemical_list: D000981:Antiprotozoal Agents; D016207:Cytokines; D016877:Oxidants; D011134:Polysaccharides; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; C007789:fucoidan